This invention relates to fluid separator apparatus and more particularly to liquid-gas separators adapted for use with submergible downhole pumps.
Liquid-gas separators are used downhole in oil-producing wells to separate gas from crude oil before the oil enters the downhole pump. Any gas present in the oil supplied to the pump tends to restrict the flow through the pump and to reduce its volumetric efficiency. If excessive quantities of gas are present in the oil, gas lock can occur which completely restricts the flow of the oil through the pump, requiring that the pump be shut down for later restart. An effective liquid-gas separator reduces the possibility of gas lock and enables the pump to operate continuously and efficiently to pump more oil.
The prior art is replete with liquid-gas separators for downhole use. U.S. Pat. No. 3,887,342 to Bunnelle, issued June 3, 1975, and U.S. Pat. No. 4,088,459 to Tuzson, issued May 9, 1978 disclose centrifugal-type liquid-gas separators. U.S. Pat. No. 2,969,742 to Arutunoff, issued Jan. 31, 1961, and assigned to the same assignee as the present invention, discloses a reverse flow-type liquid-gas separator. U.S. Pat. No. 4,231,767 to Acker, issued Nov. 4, 1980, also assigned to the same assignee as the present invention, discloses a screen-type liquid-gas separator. Although known centrifugal-type separators may perform satisfactorily at low to moderate flow rates, they do not operate well at high flow rates, or with high volumetric ratios of gas to liquid, and they are unable to match the requirements of many high-capacity submergible pumps, resulting in the pump being "starved" and its output being reduced. Reverse flow-type separators also suffer from the same disadvantages. Screen-type separators may perform well at high flow rates. However, over a period of time, their screens tend to become clogged, which reduces their capacity and effectiveness.
It is desirable to provide liquid-gas separators which overcome these and other disadvantages of known separators, and it is to this end that the present invention is directed.